EMERGENCY MANAGEMENT OF ASTHMA: FREQUENT LOW DOSE NEBULIZED SALBUTAMOL

The bronchodilator response to nebulized salbutamol in stable asthmatics reaches a peak at 20-30 mins and is maintained for 60 mins. However, clinical observations suggest that in acute asthma, the duration of this peak effect is shorter. The aim of this study was to examine the effect of frequent administration of low doses of salbutamol during the initial management of acute asthma. 22 children aged 6-17 years who presented to the Emergency Department with acute asthma were assessed by measurement of FEV1 initially and at 20 minute intervals for 2½ hours. All children received an initial dose of 0.15 mg/kg salbutamol in 2 ml of normal saline via a nebulizer. Thereafter, those in group A (8 patients) received the same dose at 60 min. intervals for 2 further doses and those in group B (14 patients) received 0.05 mg/kg salbutamol at 20 min. intervals for 6 doses. Mean FEV1 (% predicted) for both groups were similar initially (A=33, B=29) at 20 min. (A=46, B=45), and at 2½ hours (A=54, B=57). FEV1 in group A deteriorated between doses and maximal bronchodilatation was not achieved until 2½ hours. Whereas FEV1 in group B was maximal at 60 min. and failed to show further improvements in spite of additional medication. Air flow limitation in acute asthma is multifactorial and it would appear that maximal bronchodilator effect of salbutamol can be achieved by 60 minutes and maintained by frequent administration of small doses.